Heretofore there have been proposed successive screw feeder drivers capable of successively feeding and driving screws into a plate such as, for example, wooden plate or metallic plate to fix the plate to a wall surface, a floor surface, or the like, (hereinafter referred to as "a wall surface or the like"). For example, a conventional successive screw feeder driver of this type is shown in FIG. 5. In this conventional successive screw feeder driver 51, a grip handle 54 is formed and mounted in a generally T-shape below a screw driving mechanism body 53 which incorporates a drive unit 52 therein, and a screw driving rod-like bit 55, which corresponds to the screwdriver as a commonly-used tool, is connected to the drive unit 52 in the front portion of the screw driving mechanism body 53. The bit 55 is rotated to drive screws. This type is popular.
In the above conventional screw feeder driver 51, however, when the operator grasps the grip handle 54 and pushes the tip end of the bit 55 against the surface of a plate or the like, if the screw driving mechanism body 53 is pushed strongly against a wall surface or the like during the work, a force of rotating downward to the front (in the direction of arrow A) is generated in the body 53, centered on the screw portion being driven to the wall surface or the like, because a pushing direction F of the operator's hand and an axial direction of a virtual rotation line CL of the bit 55 which drives the screw are vertically spaced and separated from each other. Therefore, the operator is required to not only push the tip end of the bit in the screw driving direction continually but also prevent the lower portion of the grip handle 54 from rotating downward to the front (in the arrow A direction). Thus, the operator is required to apply an extra force to the wrist, and there arises the problem that when the work is continued over a long time, not only the operator's palm which grasps the grip handle but also his or her wrist is apt to become tired to excess.
In the conventional successive screw feeder driver 51, if the screw driving mechanism body 53 tilts during the screw driving work, the screw will be driven inclinedly relative to the surface of the plate or the like, so that a part of the screw head is protruded from the wall surface or the like and from the surface of the plate. Thus, the appearance of the screw after driving is deteriorated.
In the case of the grip handle 54 of a simple, generally cylindrical shape used in the conventional successive screw feeder driver 51, as shown in FIG. 6, there occurs a clearance between the surface of the grip handle 54 and the recess of the palm C. In other words, the palm C does not fit the rear face of the grip handle 54 perfectly. Accordingly, as the screw driving work is continued over a long time, the operator becomes tired in the palm and the grasping power is deteriorated.
The present invention has been accomplished in view of the above-mentioned problems and it is an object of the invention to provide a successive screw feeder driver wherein a screw driving direction of a grip handle, namely a virtual rotation line of a bit, and a pushing direction line of an operator's hand are made substantially coincident with each other, a housing which houses a drive unit therein is positioned above the position where the virtual rotation line of the bit is formed, and a supporting and pushing portion of a grip handle is formed on the lower surface of the housing, thereby permitting a pushing force of the palm to be transmitted to the front of the bit axis exactly and effectively at the time of driving a screw.